1. Field of the Invention
The present invention relates to the biological control of plant diseases (e.g. either pre-harvest or postharvest diseases) in agricultural commodities such as fruit. More particularly, this invention relates to: (1) methods for biologically controlling plant diseases (such as post harvest rots) on agricultural commodities using either, (a) at least one calcium salt and at least one microorganism which is an antagonist to plant pathogens, or (b) at least one microorganism which is an antagonist against plant pathogens but is not antibiotic; (2) compositions useful in such methods, and; (3) manufactures produced by such methods.
2. Description of Prior Art
Postharvest diseases of fruit cause 15 to 25% losses yearly in the fruit industry worldwide. Fungicides, the major weapon in combatting these diseases, are often ineffective and pose hazards to humans and the environment. Therefore, a critical need exists for new methods to control postharvest diseases without posing such hazards to humans or the environment.
Recently, it has been shown that the postharvest treatment of fruit with antagonistic microorganisms is an effective approach to the control of postharvest rots. Remarkable success was shown in the control of brown rot in peaches caused by Monilinia fructicola (Wint.) Honey with Bacillus subtilis. Pusey et al. [Plant Dis. 86:753-756 (1986)]. De Matoswas able to reduce mold incidence from 35% to 8% when a species of Trichoderma was inoculated with Penicillium digitatum into lemon peel. De Matos, Ph.D. Dissertation, University of California, Riverdale, (1983). Singh and Deverall demonstrated biocontrol with bacterial antagonists to the citrus pathogens Alternaria citri Pierce, Geotrichum candidum link. ex Pers., and P. digitatum. Singh et al. [Trans. Br. Mycol. Soc. 83:487-490 (1983)]. Dipping wounded citrus fruit in suspensions of bacterial cells, particularly a strain of Bacillus subtilis (Ehrenber) Cohn, delayed decay by the three rot pathogens.